Damped anti-rotational systems

ABSTRACT

A damped anti-rotational system is provided comprising a pawl carrier having an axis of rotation, a pawl pivotably mounted to the pawl carrier on a pivot joint, the pawl having a contact portion and a counterweight portion, a stop pin axially disposed in the pawl carrier and configured to contact the contact portion of the pawl in response to radially inward movement of the pawl, wherein the stop pin is mounted to the pawl carrier at a forward portion of the stop pin and an aft portion of the stop pin, wherein a forward O ring is disposed on the forward portion of the stop pin and an aft O ring is disposed on the aft portion of the stop pin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S.application Ser. No. 15/601,663, filed May 22, 2017 and entitled “DAMPEDANTI-ROTATIONAL SYSTEMS,” ('663 application). The '663 application is adivisional of and claims priority to U.S. application Ser. No.14/660,537, filed Mar. 17, 2015 and entitled “DAMPED ANTI-ROTATIONALSYSTEMS” (the '537 application). The '537 application claims the benefitof U.S. Provisional Application No. 61/977,812, filed Apr. 10, 2014 andentitled “DAMPED ANTI-ROTATIONAL SYSTEMS.” The aforementionedapplications are incorporated herein by reference in their entirety.

FIELD

The present disclosure relates to damped anti-rotational systems andmethods, and more specifically, to damped anti-rotational systems andmethods applicable to turbine engines.

BACKGROUND

Turbine engines typically windmill when idle. A turbine engine willoften windmill due to wind blowing through the engine. Many times, windenters through the engine outlet, causing the engine to windmill inreverse. Many turbine engines do not have a feature to prevent thereverse wind milling of the engine or utilize a complex and/or heavysystem to accomplish this feature. Moreover, forward wind milling isoften desired, for example, to enable the engine to more readily restartin flight. Reverse wind milling is not desired, for example, to reducewear on the engine when idle. A turbine engine typically has a system tofacilitate lubrication of rotating components when idle, but often thissystem only lubricates the rotating components when the engine isforward wind milling. Thus, reverse wind milling is often not desired.

SUMMARY

A damped anti-rotational system is provided comprising a pawl carrierhaving an axis of rotation, a pawl pivotably mounted to the pawl carrieron a pivot joint, the pawl having a contact portion and a counterweightportion, a stop pin axially disposed in the pawl carrier and configuredto contact the contact portion of the pawl in response to radiallyinward movement of the pawl, wherein the stop pin is mounted to the pawlcarrier at a forward portion of the stop pin and an aft portion of thestop pin, wherein a forward O ring is disposed on the forward portion ofthe stop pin and an aft O ring is disposed on the aft portion of thestop pin.

A damped anti-rotational system is provided comprising a pawl carrierhaving an axis of rotation, a pawl pivotably mounted to the pawl carrieron a pivot joint, the pawl having a contact portion and a counterweightportion, an stop pin axially disposed in the pawl carrier and configuredto contact the contact portion of the pawl in response to radiallyinward movement of the pawl, wherein a central portion of the stop pinis wrapped in an elastic material.

A damped anti-rotational system is provided comprising a pawl carrierhaving an axis of rotation, a pawl pivotably mounted to the pawl carrieron a pivot joint, the pawl having a contact portion and a counterweightportion, a springboard radially protruding from the pawl carrier andconfigured to contact the contact portion of the pawl in response toradially inward movement of the pawl.

In various embodiments, the forward O ring is disposed on a forwardgroove of the stop pin. In various embodiments, the aft O ring isdisposed on an aft groove of the stop pin. In various embodiments,forward portion of the stop pin is mounted in an indentation of the pawlcarrier. In various embodiments, the aft portion of the stop pin ismounted in an aperture of the pawl carrier. In various embodiments, theforward O ring comprises a polymeric material. In various embodiments,there is an air gap between the pawl carrier and the forward portion ofthe stop pin. In various embodiments, the stop pin comprises at leastone of stainless steel and Greek Ascoloy. In various embodiments, theforward O ring comprises an elastic material. In various embodiments,the aft O ring comprises an elastic material. In various embodiments,the stop pin comprises at least one of stainless steel and GreekAscoloy. In various embodiments, a forward portion of the stop pin andan aft portion of the stop pin are exposed. In various embodiments, theelastic material is a polymeric material. In various embodiments,forward portion of the stop pin is mounted in an indentation of the pawlcarrier. In various embodiments, the stop boss is integral to the pawlcarrier. In various embodiments, the elastic material is coupled to thestop boss by an adhesive. In various embodiments, the elastic materialis a polymeric material. In various embodiments, the pawl carriercomprises at least one of stainless steel and Greek Ascoloy.

BRIEF DESCRIPTION OF THE D WINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements.

FIG. 1 illustrates a turbofan engine;

FIGS. 2A and 2B illustrate a pawl carrier according to variousembodiments;

FIGS. 3A and 3B illustrate a pawl and pawl carrier according to variousembodiments;

FIG. 4 illustrates a stop pin and pawl carrier according to variousembodiments;

FIG. 5 illustrates a wrapped stop pin according to various embodiments;

FIG. 6 illustrates a stop boss according to various embodiments; and

FIG. 7 illustrates a springboard stop according to various embodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration and their best mode. While these exemplary embodiments aredescribed in sufficient detail to enable those skilled in the art topractice the inventions, it should be understood that other embodimentsmay be realized and that logical, chemical and mechanical changes may bemade without departing from the spirit and scope of the disclosure.Thus, the detailed description herein is presented for purposes ofillustration only and not of limitation. For example, the steps recitedin any of the method or process descriptions may be executed in anyorder and are not necessarily limited to the order presented.

Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact.

As used herein, phrases such as “make contact with,” “coupled to,”“touch,” “interface with” and “engage” may be used interchangeably.

As used herein, “aft” refers to the direction associated with the tail(e.g., the back end) of an aircraft, or generally, to the direction ofexhaust of the gas turbine engine. As used herein, “forward” refers tothe direction associated with the nose (e.g., the front end) of anaircraft, or generally, to the direction of flight or motion.

In various embodiments and with reference to FIG. 1, a gas turbineengine 20 is provided. Gas turbine engine 20 may be a two-spool turbofanthat generally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mayinclude, for example, an augmentor section among other systems orfeatures. In operation, fan section 22 can drive air along a bypassflow-path B while compressor section 24 can drive air along a coreflow-path C for compression and communication into combustor section 26then expansion through turbine section 28. Although depicted as aturbofan gas turbine engine 20 herein, it should be understood that theconcepts described herein are not limited to use with turbofans as theteachings may be applied to other types of turbine engines includingthree-spool architectures.

Gas turbine engine 20 may generally comprise a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A-A′ relative to an engine static structure 36 viaseveral bearing systems 38, 38-1, and 38-2. It should be understood thatvarious bearing systems 38 at various locations may alternatively oradditionally be provided, including for example, bearing system 38,bearing system 38-1, and bearing system 38-2.

Low speed spool 30 may generally comprise an inner shaft 40 thatinterconnects a fan 42, a low pressure (or first) compressor section 44and a low pressure (or first) turbine section 46. Inner shaft 40 may beconnected to fan 42 through a geared architecture 48 that can drive fan42 at a lower speed than low speed spool 30. Geared architecture 48 maycomprise a gear assembly 60 enclosed within a gear housing 62. Gearassembly 60 couples inner shaft 40 to a rotating fan structure. Highspeed spool 32 may comprise an outer shaft 50 that interconnects a highpressure (or second) compressor section 52 and high pressure (or second)turbine section 54. A combustor 56 may be located between high pressurecompressor 52 and high pressure turbine 54. A mid-turbine frame 57 ofengine static structure 36 may be located generally between highpressure turbine 54 and low pressure turbine 46. Mid-turbine frame 57may support one or more bearing systems 38 in turbine section 28. Innershaft 40 and outer shaft 50 may be concentric and rotate via bearingsystems 38 about the engine central longitudinal axis A-A′, which iscollinear with their longitudinal axes. As used herein, a “highpressure” compressor or turbine experiences a higher pressure than acorresponding “low pressure” compressor or turbine.

The core airflow C may be compressed by low pressure compressor 44 thenhigh pressure compressor 52, mixed and burned with fuel in combustor 56,then expanded over high pressure turbine 54 and low pressure turbine 46.Mid-turbine frame 57 includes airfoils 59 which are in the core airflowpath. Turbines 46, 54 rotationally drive the respective low speed spool30 and high speed spool 32 in response to the expansion.

Gas turbine engine 20 may be, for example, a high-bypass geared aircraftengine. In various embodiments, geared architecture 48 may be anepicyclic gear train, such as a star gear system (sun gear in meshingengagement with a plurality of star gears supported by a carrier and inmeshing engagement with a ring gear) or other gear system. Geararchitecture 48 may have a gear reduction ratio of greater than about2.3 and low pressure turbine 46 may have a pressure ratio that isgreater than about 5. In various embodiments, the bypass ratio of gasturbine engine 20 is greater than about ten (10:1). In variousembodiments, the diameter of fan 42 may be significantly larger thanthat of the low pressure compressor 44, and the low pressure turbine 46may have a pressure ratio that is greater than about 5:1. Low pressureturbine 46 pressure ratio may be measured prior to inlet of low pressureturbine 46 as related to the pressure at the outlet of low pressureturbine 46 prior to an exhaust nozzle. It should be understood, however,that the above parameters are exemplary of various embodiments of asuitable geared architecture engine and that the present disclosurecontemplates other gas turbine engines including direct drive turbofans.

With reference to FIG. 1, gas turbine engine 20 may generally includemultiple of modules including for example, a fan case module 61, anintermediate case module 63, a Low Pressure Compressor (LPC) module 64,a High Pressure Compressor (HPC) module 66, a diffuser module 68, a HighPressure Turbine (HPT) module 70, a mid-turbine frame (MTF) module 72, aLow Pressure Turbine (LPT) module 74, and a Turbine Exhaust Case (TEC)module 76.

As described above, an anti-rotational device may be used to preventreverse wind-milling in a turbofan engine. In particular, ananti-rotational device may be disposed in the low pressure turbine toprevent rotation in an undesired direction. For example, ananti-rotational device may be configured to allow rotation in a firstdirection (e.g., clockwise) and to limit all or nearly all rotation in asecond direction (e.g., counter clockwise). Moreover, an anti-rotationaldevice may be configured to limit mechanical contact at or above certainangular velocities. In that regard, lower angular velocities may beassociated with a level of mechanical contact between various componentsbut, after a low pressure turbine achieves a given angular velocity, thecontact may be reduced or eliminated. However, such anti-rotationaldevice may exhibit undesired vibration, for example, when rotationproceeds at an angular velocity below a predetermined angular velocity.

With reference to FIGS. 2A and 2B, pawl system 200 is shown. Pawlcarrier 206 is shown coupled to pawl 202. Stop pin 204 is shown disposedin pawl carrier 206. Pawl carrier 206 may comprise any number of pawls,for example, from 1 pawl to 20 pawls. In various embodiments, any numberof pawls may be used, and thus the selection of the appropriate numberof pawls and the spacing of the pawls may be tuned in response to designweight constraints, footprint, and other manufacturing concerns. Invarious embodiments, pawl carrier 206 comprises three pawls distributeduniformly about the circumference of pawl carrier 206.

Pawl 202 may be comprised of any suitable material. For example, pawl202 may be comprised of stainless steel such as 300M stainless steeland/or a chromium-nickel-tungsten martensitic alloy (also known as GreekAscoloy). In various embodiments, various components disclosed hereinmay comprise 300M stainless steel and/or chromium-nickel-tungstenmartensitic alloy (also known as Greek Ascoloy) and/or austeniticnickel-chromium-based alloy such as Inconel® which is available fromSpecial Metals Corporation of New Hartford, N.Y., USA, or any othermetal, for example, titanium. However, in further embodiments, variouscomponents of anti-rotational devices may comprise other metals, such astungsten, aluminum, steel, or alloys, though they may further comprisenumerous other materials configured to provide mechanical resiliencyand/or support of the system when subjected to wear in an operatingenvironment or to satisfy other desired electromagnetic, chemical,physical, or biological properties such as strength, durability,ductility, heat tolerance, thermal dissipation, and footprintconstraints, among others. In various embodiments, various portions ofanti-rotational devices as disclosed herein are made of differentmaterials or combinations of materials, and/or may comprise variouscoatings.

With brief reference to FIGS. 3A and 3B, pawl 202 is shown pivotablymounted to pawl carrier 206 on a pivot joint 302. Pivot joint 302 allowspawl 202 to rotate freely about pivot joint 302. Pivot joint 302 maycomprise any suitable joint that is configured to allow pawl 202 topivot. For example, a post and bushing mating may be used as pivot joint302. Pivot joint 302 may be suitably lubricated, for example, using asolid state lubricant and/or liquid lubricant. Pivot joint 302 may alsocomprise one or more materials that are coated with or comprised of alow friction material. For example, portions of pivot joint 302 may becoated with polytetrafluoroethylene (“PTFE”). In various embodiments,pivot joint 302 is disposed at or near the geometric center of pawl 202.

With continued reference to FIGS. 2A and 3, pawl 202 comprisescounterweight portion 208 and contact portion 210. Pawl 202 may comprisea single integral piece comprising counterweight portion 208 and contactportion 210. Counterweight portion 208 may be integral to pawl 202 andmay be formed by any suitable means, for example, by forging, casting,stamping, negative manufacturing techniques, additive manufacturingtechniques and/or other methods of manufacture. Counterweight portion208 may be configured such that the center of mass of pawl 202 is moreproximate a terminus of counterweight portion 208 than a terminus ofcontact portion 210. Counterweight portion 208 may be configured to havea “scoop” or cut out and/or a portions of greater thickness and/or masswhen compared with other portions of pawl 202.

Torsion spring 304 may be disposed to exert a radial outward force uponpawl 202. In that regard, torsion spring 304 exerts a rotational forceon pawl 202 that tends to pivot pawl 202 about pivot joint 302 in aradially outward direction. Torsion spring 304 may be made from anysuitable material, for example, stainless steel.

With reference to FIG. 3B, upon rotation in clockwise direction 312,contact portion 210 may be directed radially outward with respect topawl carrier 206. With reference to FIG. 2B, as pawl carrier 206 rotatesin counterclockwise direction 214 at an angular velocity below apredetermined angular velocity, each pawl may contact structures, suchas a ratchet, disposed radially outward of pawl carrier 206. In thatregard, pawl 202 may periodically be deflected after contact with othercontact structures.

In that regard, a stop pin may be disposed in an axial direction andprovide a contact point for pawl 202 and contact portion 210 inparticular, to prevent pawl 202 from contacting pawl carrier 206. Thus,stop pin 204 is configured to interact with contact portion 210 inresponse to radially inward movement of pawl 202.

FIG. 4 illustrates a cross sectional view of stop pin 204 along the lineA-A′ shown in FIG. 2B. Line A-A′ is disposed such that point A isforward of point A′. With reference to FIG. 4, stop pin 204 is mountedto pawl carrier 206 at forward portion 410 of stop pin 204 and at aftportion 412 of the stop pin 204. Forward portion 410 of the stop pin 204is mounted in an indentation 406 and has forward groove 414. Aft portion412 of the stop pin 204 is mounted in an indentation 408 and has aftgroove 416. O ring 402 is disposed in forward groove 414 and O ring 404is disposed in aft groove 416. Stated another way, O ring 402 is wrappedaround forward groove 414 and O ring 404 is wrapped around aft groove416.

O ring 402 and O ring 404 may be comprised of any suitable material. Invarious embodiments, O ring 402 and O ring 404 may comprise an elasticmaterial and/or a deformable material. In various embodiments, O ring402 and O ring 404 may comprise a polymeric material, for example, athermoplastic. In various embodiments, O ring 402 and O ring 404 maycomprise PTFE.

O ring 402 and O ring 404, in various embodiments, may take geometriesother than that of a ring or an “O.” In that regard, O ring 402 and Oring 404 may have one or more of a triangular profile and a rectangularprofile.

In that regard, in various embodiments, stop pin 204 may not be incontact with pawl carrier 206. For example, contact points 418 and 420show contact between O ring 402 and pawl carrier 206. Stop pin 204 doesnot contact pawl carrier 206 proximate forward portion 410 of the stoppin 204. Similarly, contact points 422 and 424 show contact between Oring 404 and pawl carrier 206. Stop pin 204 does not contact pawlcarrier 206 proximate aft portion 412 of the stop pin 204. In variousembodiments, in response to impact from a pawl, stop pin 204 may causeone or more of O ring 402 and O ring 404 to deform. In such a scenario,stop pin 204 may contact pawl carrier 206 proximate one or more of aftportion 412 and forward portion 410 of stop pin 204.

With reference to FIG. 5, damped pawl system 500 is illustrated. Pawl502 is illustrated as rotating about pivot joint 504. Stop pin 508 issupported by a pawl carrier, though the pawl carrier is not shown forclarity. Stop pin 508 is wrapped in elastic material 506. In thatregard, in response to rotation of pawl 502 in a counterclockwisedirection, pawl 502 makes contact with all or at least a position ofelastic material 506. Stop pin 508 may be mounted to a pawl carrierdirectly or may include O rings disposed between at least a portion ofstop pin 508 and the pawl carrier.

Elastic material 506 may be comprised of any suitable material. Invarious embodiments, elastic material 506 may comprise an elasticmaterial and/or a deformable material. In various embodiments, elasticmaterial 506 may comprise a polymeric material, for example, athermoplastic and/or a rubber material, whether natural or synthetic. Invarious embodiments, elastic material 506 may comprise PTFE.

Elastic material 506 may be configured to damp the impact of pawl 502 onstop pin 508. By lessening the rebound of pawl 502 after contact withstop pin 508, pawl 502 may oscillate with less amplitude than would beconventional.

With reference to FIG. 6, damped pawl system 600 is illustrated. Pawl602 is illustrated as rotating about pivot joint 604. Stop boss 606 isshown as integral to a pawl carrier 610. Stop boss 606 may thereforecomprise a raised surface or protrusion from the surface of the pawlcarrier. Stop boss 606 is capped by elastic material 608. In thatregard, in response to rotation of pawl 602 in a counterclockwisedirection, pawl 602 makes contact with all or at least a portion ofelastic material 608.

Elastic material 608 may be comprised of any suitable material. Invarious embodiments, elastic material 608 may comprise an elasticmaterial and/or a deformable material. In various embodiments, elasticmaterial 608 may comprise a polymeric material, for example, athermoplastic and/or a rubber material, whether natural or synthetic. Invarious embodiments, elastic material 608 may comprise PTFE.

Elastic material 608 may be configured to damp the impact of pawl 602 onstop boss 606. By lessening the rebound of pawl 602 after contact withstop boss 606, pawl 602 may oscillate with less amplitude than would beconventional.

With reference to FIG. 7, damped pawl system 700 is illustrated. Pawl703 is illustrated as rotating about pivot joint 704. Stop attachment708 is shown a point on a pawl carrier 710. Stop attachment 708 maytherefore comprise a raised surface or protrusion from the surface ofthe pawl carrier or may merely represent the point on pawl carrier wherespringboard 706 is coupled to the pawl carrier. Stop attachment 708 iscoupled to springboard 706. In that regard, in response to rotation ofpawl 703 in a counterclockwise direction, pawl 703 makes contact withall or at least a portion of springboard 706. Springboard 706 extendscircumferentially towards pawl 703. Springboard 706 may contact pawlcarrier in response to contact with pawl 703.

Springboard 706 may be comprised of any suitable material. In variousembodiments, springboard 706 may comprise an elastic material and/or adeformable material. In various embodiments, springboard 706 maycomprise a polymeric material, for example, a thermoplastic and/or arubber material, whether natural or synthetic. In various embodiments,springboard 706 may comprise PTFE.

Springboard 706 may be configured to damp the impact of pawl 703 on pawlcarrier. By lessening the rebound of pawl 703 after contact with thepawl carrier, pawl 703 may oscillate with less amplitude than would beconventional.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f), unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

1. A damped anti-rotational system comprising: a pawl carrier having anaxis of rotation; a pawl pivotably mounted to the pawl carrier on apivot joint, the pawl having a contact portion and a counterweightportion; and an stop boss radially protruding from the pawl carrier andconfigured to contact the contact portion of the pawl in response toradially inward movement of the pawl, wherein a central portion of thestop boss is capped with an elastic material.
 2. The dampedanti-rotational system of claim 1, wherein the stop boss is integral tothe pawl carrier.
 3. The damped anti-rotational system of claim 1,wherein the elastic material is coupled to the stop boss by an adhesive.4. The damped anti-rotational system of claim 1, wherein the elasticmaterial is a polymeric material.
 5. The damped anti-rotational systemof claim 1, wherein the pawl carrier comprises at least one of stainlesssteel and Greek Ascoloy.